Summary
Cardiac surgery is complicated by the occurrence of post-operative bleeding due to
platelet dysfunction. This is largely caused by platelet activation and consumption
during cardiopulmonary bypass. Patients undergoing cardiac surgery requiring cardiopulmonary
bypass were studied to determine whether early platelet changes due to bypass could
be inhibited using the platelet-selective nitric oxide donor S-nitroso-glutathione
(GSNO). Flow cytometry was used to measure platelet surface expression of P-selectin
(an α-granule protein) and glycoproteins (GP) IIb/IIIa and Ib (mediators of aggregation
and adhesion) before and 5 and 10 min after commencing cardiopulmonary bypass, in
6 controls and 6 patients receiving GSNO 50 μg/min. Platelet P-selectin expression
increased during bypass both in controls and patients receiving GSNO. Glycoproteins
IIb/IIIa and Ib fell during bypass in control and GSNO-treated patients. There was
no difference between control and GSNO-treated groups. Thus no significant platelet
inhibition by S-nitrosoglutathione was demonstrated under these conditions.